Grounded duplex telegraph system



April 10, 1928. 1,665,297

S. I. CORY v GROUNDED DUPLEX TELEGRAPH SYSTEM Filed June 26. 1926 INVENTOR @SZ Z 5013/ ference with telegraph Patented Apr. 10, 1928.

1 UNITED raters fried-QR. v

sAmUEL I. CORY, or TOWACO, NEW JERSEY, ASSIGNOR- To AMERICANITELEQPII-IVONE Ann TELEGRAPH COMPANY,

A CRFCRATION OF NEW YORK.

GRoInvDED n'UPLnX TELEGRAPH SYSTEM.

Application fi ea'Juneae, i92 Serial No. 118,754.

This invention relates to grounded direct currenttelegraph systems, and more particularlyto the duplex repeater circuits employed in such systems.

I The object of the invention is to provide improved arrangements for reducing intersystems from alternating current power transmission systems.

It has been the practice heretofore to emplo resonant shunts connected across the receiving relay windings of telegraph sys-- terms of the classto which the i-nvention relates. These shunt circuits are tuned to the frequency of the interfering power currents offering a low'impedanceto these currents and a high impedance to the signaling currents. Y

In accordance with the invention described hereinafter,

cuit'arrangement including anti-resonant ele-v ments.

' 1n series with the line .the interfering power and a winding 4.

condenser G and In the use of anti-resonant arrangements resorted to heretofore, it has been necessary to employ separate inductances in the line and in the artificial line, and with such arrangements there is an undesirable effect on signalsoutgoing from the repeater.

The drawing shows as an illustration a differential duplex arrangement modified according to my invention. The circuit which is shown diagrammatically in- Figure 1 of the drawing, and in a similar manner and a modified form in Fig. 2, includes as elements old and well understood'in the art, a line, a balancing artificial line, a sending relay and a receiving relay having a winding W and a winding W in series with the artificial liner I I In the arrangement of F ig. 1, I make use of a transformer comprising a windingfi The windings 3 and tare connecteddifferentially with respect to sigrelay Condensers G and C are windings 3 and 4, respecof' the system.

connected across tively. The values of the capacity the capacity of the condenser 0, should be large. Furthermore, the capacities, in combination with the windings, should offer high impedance, looking into the transformers, to the frequency of current. With this arrangement, the series impedance intro I provide a novel ciron the winding Wr spect to the outgoing complete protection of the duced in the line by the anti-resonant ele ments will be small.

The chief advantage of the arrangement 1 described above is the'considerable reduction of the efiect'of the anti-resonant elements on both the outgoing and incoming telegraph signals. In a "modifie form of the circuit shown in Fig. 2, the'receiv'ing relay is shown with" a firstwinding'W in series with the line, a second winding in series with the artifi cial line, and a" third XvindingW This third winding is associated with the transformerv arrangement and the tuned circuits as follows: I provide twotransformers, the primary'winding 5 of the one transformer being associated with a'condenser G, in the line, and the primary-winding 7 of the sec (1 transformer being associated with a condenser G inthe artificialv line. The secondary windings of the two transformers, 6 and .8, respectively, are connected in series with of the receiving relay. The formed by the inductance tuned circuits looking into winding 5 of the first transformer and the condenser C and the induct- 1 ance looking into winding 7 of the second transformer and the condenser-C are so designed that there islittle'effect on either outgoing or incoming telegraph signals It is that the primary windlngs 5 g to be noted and 7 are connected diiferentiallywith re-;

signals. The interfermg current flowing the winding W will be in such a direction as to neutralize the iiow of interfering current in the relay wind- Y mgs W and W With proper proportions of the transformers and the winding W the arrangement will afford substantially against interfering power currents of a given frequency and will have practically no effect on either incoming or outgoing telegraph signals.

What is claimed is:

1. In a duplextelegraph repeater system, a line, an artificial line, a sending relay, a receiving relay, a transformer arrangement associated with the line and the artificial line, a tuned circuit in the line anti-resonant at the frequencies of interfering and a tuned circuit in the artificial line antiresonant at said frequencies, each of said currents,

merits one Winding of said transformer arrangement.

'2. In a duplex telegraph repeater system,

a line, an artificial line, a sending relay, a receivlng relay, a transformer, a first tuner circuit in the line including one Winding of said transformer, and a second tuned'circuit.

in the artificial'line including the other Winding of said transformer, said two windings of thetransformer being connected dif ferentially with respect to signalssent out by the sending relay, and said tuned circuits being anti eresonant at the frequencies of interfering currents. V V

3. In a duplex telegraph repeater system, a 1.1118, an artificlal line, a send1ng relay, a

' 4 receiving relay having a firstwinding in the a line, a second windingin the artific al line,

and a third winding, two transformers, a'tuned circuit in the line including the pr mary v inding of one of said transformers,

:and a tuned circuit in the artificial line in cluding the primary windingof the other of said transformers, the secondary WlIldlhgS of said transformers being connected in ,se-

ries withv the third inding of the receiving 9 v rear-1,29?

relay, resonant at the frequencles of interfering alternatlng currents.

In a duplex telegraph'repeater system, a line, an artificial line, a sending relay, a

receiving relay having a first Winding in the line, a second Winding-in the artificial line,

ies With the third Windingof the receiving relay and the primary windings thereof being connected differentially with respect to signals sent to the line by the sending relay, said tuned circuitsbeing anti-resonant at the frequencies of interfering alternating currents. v y

In testimon whereof, I have signed my name to this specification this 24th day of June, 1926.

SAMUEL I. coRY;

and said tuned circuits being anti} 

